package richard.and.a3dcarousel;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Richard Chamberlain on 2017/10/31 17:27.
 */

public class OpenGLRenderer implements GLSurfaceView.Renderer {
    int angle = 0;

    // Initialize our square.
//    Square square = new Square();
//    FlatColoredSquare flatColoredSquare = new FlatColoredSquare();
    SmoothColoredSquare smoothColoredSquare = new SmoothColoredSquare();
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        // Set the background color to black ( rgba ).
        // OpenGL docs.
        gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
// Enable Smooth Shading, default not really needed.
        // OpenGL docs.
        gl.glShadeModel(GL10.GL_SMOOTH);
// Depth buffer setup.
        gl.glClearDepthf(1.0f);// OpenGL docs.
// Enables depth testing.
        gl.glEnable(GL10.GL_DEPTH_TEST);// OpenGL docs.
// The type of depth testing to do.
        gl.glDepthFunc(GL10.GL_LEQUAL);// OpenGL docs.
// Really nice perspective calculations.
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, // OpenGL docs.
                GL10.GL_NICEST);


    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
// Sets the current view port to the new size.
        gl.glViewport(0, 0, width, height);// OpenGL docs.
// Select the projection matrix
        gl.glMatrixMode(GL10.GL_PROJECTION);// OpenGL docs.
// Reset the projection matrix
        gl.glLoadIdentity();// OpenGL docs.
// Calculate the aspect ratio of the window
        GLU.gluPerspective(gl, 45.0f,
                (float) width / (float) height,
                0.1f, 100.0f);
// Select the modelview matrix
        gl.glMatrixMode(GL10.GL_MODELVIEW);// OpenGL docs.
// Reset the modelview matrix
        gl.glLoadIdentity();// OpenGL docs.
    }

    @Override
    public void onDrawFrame(GL10 gl) {
// Clears the screen and depth buffer.
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT
                | GL10.GL_DEPTH_BUFFER_BIT);
// Replace the current matrix with the identity matrix
        gl.glLoadIdentity();
// Translates 10 units into the screen.
        gl.glTranslatef(0, 0, -10);
// SQUARE A
// Save the current matrix.
        gl.glPushMatrix();
// Rotate square A counter-clockwise.
        gl.glRotatef(angle, 0, 0, 1);
// Draw square A.
        smoothColoredSquare.draw(gl);
// Restore the last matrix.
        gl.glPopMatrix();
// SQUARE B
// Save the current matrix
        gl.glPushMatrix();
// Rotate square B before moving it,
//making it rotate around A.
        gl.glRotatef(-angle, 0, 0, 1);
// Move square B.
        gl.glTranslatef(2, 0, 0);
        // Scale it to 50% of square A
        gl.glScalef(.5f, .5f, .5f);
// Draw square B.
        smoothColoredSquare.draw(gl);
// SQUARE C
// Save the current matrix
        gl.glPushMatrix();
// Make the rotation around B
        gl.glRotatef(-angle, 0, 0, 1);
        gl.glTranslatef(2, 0, 0);
// Scale it to 50% of square B
        gl.glScalef(.5f, .5f, .5f);
// Rotate around it's own center.
        gl.glRotatef(angle*10, 0, 0, 1);
// Draw square C.
        smoothColoredSquare.draw(gl);
// Restore to the matrix as it was before C.
        gl.glPopMatrix();
        // Restore to the matrix as it was before B.
        gl.glPopMatrix();
// Increse the angle.
        angle++;
    }

}
